The minor opposition Unified Progressive Party was disbanded Friday in a first-ever decision by the Constitutional Court that a political party is unconstitutional.

With the ruling taking immediate effect, the party no longer exists as a political entity, and UPP Reps. Kim Mi-hyui, Kim Jae-yeon, Lee Sang-kyu, Lee Seok-ki and Oh Byung-yun lost their status as members of the parliament. Three of the seats will be filled in the by-elections in April, while the two proportional representatives’ seats will be left vacant.

All assets including government subsidies and funds raised by supporters will be given over to the government. The party had received about 6.1 billion won ($5.5 million) in government subsidies since the petition for its disbandment was filed, and the party’s current assets stand at about 1.36 billion won.

Constitutional Court President Park Han-chul (Yonhap)

The ruling comes more than a year after a petition from the Ministry of Justice. On Nov. 5, 2013, the Justice Ministry filed a constitutional petition calling for the UPP to be disbanded, claiming that the party was pro-North Korea. Citing the UPP’s constitution, which closely resembles North Korean ideology, the Justice Ministry argued that the party should be disbanded.

Although the Constitutional Court concluded the UPP’s constitution could not be definitively linked to North Korea, the court judged that the party aimed to overthrow South Korea’s government.

Saying that the party was directed mainly by individuals linked to former pro-North Korean organizations, the court said that the UPP’s fundamentals were based on Pyongyang’s ideals.

“It is deemed that the defendant’s true purpose and actions are first to realize progressive democracy through violence, and ultimately to realize North Korean-style socialism,” the court said in the ruling.

UPP chief Lee Jung-hee (Yonhap)

Following the ruling, UPP chief Lee Jung-hee said that she “failed in my last duty to defend democracy” and accused the Park Geun-hye administration of tyranny.

“Democracy has completely fallen. The Park Geun-hye administration has dragged South Korea down to (the level of) a dictatorial nation,” Lee said. Referring to parts of the UPP constitution that focus on the working class, she claimed that the ruling banned “politics for the people.”

“A time of darkness in which the freedom to speak and to congregate is completely denied begins again.”

The government, for its part, said that it accepted the decision and would take the necessary steps to complete the UPP’s dissolution.

“Defending constitutional order in South Korea is the government’s most basic duty. The government will not overlook any attempt to damage the liberal democratic system,” Prime Minister Chung Hong-won said.

The ruling Saenuri Party welcomed the decision, saying that it was a victory of “the Constitution, and liberal democracy.” The party did not miss the opportunity to level an attack against the opposition bloc, highlighting that the coalition of opposition parties in the 2012 general elections allowed UPP lawmakers into the parliament.

“There must never again be a party that plays host to pro-North Korean forces,” Saenuri Party spokesperson Rep. Park Dae-chul said.

“The party that formed an alliance with the UPP, and those central to the move must reflect on their actions.”

The main opposition New Politics Alliance for Democracy met the decision with cautious criticism, saying that the people should have been given the choice of whether or not to disband the UPP.